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CS320 Web and Internet Programming JSP Standard Tag Library (JSTL)

Learn how to use JSP Standard Tag Library (JSTL) to create custom tags in web programming. Examples and usage for JSTL tags and functions.

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CS320 Web and Internet Programming JSP Standard Tag Library (JSTL)

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  1. CS320 Web and Internet ProgrammingJSP Standard Tag Library (JSTL) Chengyu Sun California State University, Los Angeles

  2. Custom Tags in ASP.NET <p>Enter a number from 1 to 100: <asp:TextBox id="tbox1" runat="server" /> <asp:Button Text="Submit" runat="server" /> </p>

  3. Custom Tags in ColdFusion <cfform action = “cftextinput.cfm” method=“post”> <cftextinput name = “myInput” message = “This field must not be blank” required = “Yes” /> <input type = “Submit” value =“submit” /> </cfform>

  4. Simple JSTL Example <%@ page contentType="text/html" %> <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> <html><head><title>JSTL Hello</title></head> <body> <c:out value="Hello World in JSTL." /> </body> </html>

  5. taglib Directive • URI • A unique identifier for the tag library • NOT a real URL • Prefix • A short name for the tag library • Could be an arbitrary name

  6. JSP Standard Tag Library (JSTL) http://download.oracle.com/docs/cd/E17802_01/products/products/jsp/jstl/1.1/docs/tlddocs/index.html

  7. JSTL Usage Examples • Login.jsp, Members.jsp, Logout.jsp • GuestBook with Bean, EL, and JSTL • GuestBookEntry.java • GuestBookBean.java • GuestBook.jsp • AddComment.jsp

  8. Flow control <c:if> <c:choose> <c:when> <c:otherwise> <c:forEach> <c:forToken> Variable support <c:set> <c:remove> URL <c:url> <c:redirect> <c:import> <c:param> Output <c:out> Exception handling <c:catch> JSTL Core

  9. Branch Tags <c:if test=“${um.size == 0}”>No user yet.</c:if> <c:choose> <c:when test=“${um.size == 0}”> No user yet. </c:when> <c:otherwise> <%-- display the users --%> </c:otherwise> </c:choose>

  10. Loop Tags <%-- iterator style --%> <c:forEach items=“${um.users}” var=“user”> ${user.username} <br /> </c:forEach> <%-- for loop style --%> <c:forEach begin=“0” end=“${um.size}” step=“1” var=“i”> ${um.users[i].username} <br /> </c:forEach> <forToken ....> Exercise

  11. Set and Remove Scope Variables In Login.jsp <c:set var=“authorized” value=“true” scope=“session”/> In CheckLogin.jsp <c:if test=“${empty sessionScope.authorized}”> <c:redirect url=“Login.jsp” /> </c:if> In Logout.jsp <c:remove var=“authorized” scope=“session” />

  12. Set Bean Property • <jsp:setProperty> • name attribute must be a bean declared by <jsp:useBean> • <c:set> • target attribute can be any object with a writable property • E.g. set the property a in bean b with the value of request parameter c <c:set target=“${b}” property=“a” value=“${param.c}” />

  13. URL Tags <c:import url=“/books.xml” var=“something” /> <x:parse doc=“${something}” var=“booklist” scope=“application” /> <c:url var="url" value="/catalog" > <c:param name="Add" value="${bookId}" /> </c:url> <a href="${url}">Get book</a>

  14. Output • You want to use <c:out> if • escapeXML=true • value is a Java.io.Reader object <c:out value=“100” /> <c:out value=“${price}” /> ${100} ${price}

  15. Character Conversion • When escapeXML=true

  16. Format Date and Time <fmt:formatDate value=“${date}” type=“date” /> <fmt:formatDate value=“${date}” type=“time” /> <fmt:formatDate value=“${date}” type=“both” /> <fmt:formatDate value=“${date}” pattern=“yyyy-MM-dd hh:mm:ss a” /> See http://download.oracle.com/javase/6/docs/api/java/text/SimpleDateFormat.html for the date formatting patterns. l

  17. fn:length() fn:contains() fn:containsIgnoreCase() fn:startWith() fn:endsWith() fn:indexOf() fn:replace() fn:trim() fn:toUpperCase() fn:toLowerCase() fn:substring() fn:substringAfter() fn:substringBefore() fn:split() fn:join() fn:escapeXML() JSTL Functions

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